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Entry  Wed Oct 30 00:02:25 2013, Jenne, Update, LSC, LSC demod boards need some thought 
    Reply  Wed Oct 30 01:22:56 2013, Jenne, Update, LSC, REFL 165 demod phase adjusted 
       Reply  Wed Oct 30 01:44:13 2013, Jenne, Update, LSC, MICH and PRCL gains adjusted (Config file saved) 
          Reply  Wed Oct 30 03:36:51 2013, Jenne, Update, LSC, MICH and PRCL UGFs change with ALS enabled 
             Reply  Mon Nov 4 15:46:17 2013, Jenne, Update, LSC, Thoughts and Conclusions from last week's PRMI+2arms attempt 12x
                Reply  Tue Nov 5 19:39:27 2013, Jenne, Update, LSC, OpLev time series OpLevs_during_PRMI_2arms.pdf
    Reply  Wed Oct 30 03:33:17 2013, Rana, Update, LSC, LSC demod boards need some thought 0309.png
       Reply  Wed Oct 30 08:32:55 2013, Evan, HowTo, Computer Scripts / Programs, matplotlibrc 
Message ID: 9312     Entry time: Wed Oct 30 00:02:25 2013     Reply to this: 9313   9316
Author: Jenne 
Type: Update 
Category: LSC 
Subject: LSC demod boards need some thought 

As we are meditating on things to look at for PRMI + 2 arms, Rana brought up the question of the demod board situation. 

We then found this table on the wiki (LSC demod boards) that indicates that all of the demod boards were originally given lowpass filters, no matter the demodulation frequency.  Back in September, I switched out the low pass filter for a bandpass filter in POP110, and put in the same bandpass when putting together AS110 (elog 9100).  So, the 11MHz diodes are probably okay with lowpasses, and the 110 diodes are okay, but we need to think about all the other ones. 

We should probably do a first guess by putting in a bandpass filter, but then simulate and measure to figure out what our requirements are for attenuation at the non-demodulation frequencies for each board.

The SXBPs from Minicircuits look pretty good, but there are lots of options on their website.

 

For tonight, Rana has put a coax 100 MHz highpass filter on the input to the REFL165 demod board.

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